The present invention generally relates to devices and methods for implementing computer-aided surgical procedures and more specifically relates to devices and methods for implementing a computer-aided orthopedic surgery utilizing intra-operative feedback.
Poorly aligned or misaligned bones can occur for a variety of reasons including congenital deformity and/or accidental disfigurement. A bone can be characterized as having an actual (or anatomical) axis that runs through the cross-sectional center of the bone and a mechanical axis that extends between the joints at either end of the bone and defines the movement of the bone. In a generally straight bone with joints in line with the anatomical axis, e.g., the tibia with the knee and ankle joints, the anatomical and the mechanical axes should almost coincide. In a nonlinear bone, e.g., the femur with off-center hip joint, the mechanical axis and the anatomical axis do not coincide even when the bone is correctly aligned.
The essence of a bone deformity or disfigurement occurs when the anatomical axis is altered to a point that the mechanical (motion) axis is not in its desired position. In a straight bone such as the tibia, the amount of disfigurement can be calculated as the deviation between the anatomical axis and the mechanical axis (because the axes should align in a straight bone). This deviation can cause discomfort, joint disease, decreased range of motion, and/or numerous other medical problems. To correct or limit these improper alignments, an orthopedic surgeon may perform corrective surgery on the deformed or disfigured bone to return symmetry between the axes.
One type of corrective orthopedic surgery is an osteotomy. Osteotomies are characterized by cutting one or more slices into a deformed bone to a depth sufficient to allow the bone to be xe2x80x9crepositionedxe2x80x9d in a way that aligns the actual axis of motion with the desired axis. Typically, the bone repositioning forms a xe2x80x9cwedgexe2x80x9d or gap of open space in the bone. This space is filled via bone graft to promote new bone growth, and some type of fixation mechanism is attached to the bone to keep the bone in its new (desired) orientation during the healing process.
The movement necessary to realign a disfigured or deformed bone often requires solving complex planning calculations as well as using a certain amount of estimation based upon the experience of the orthopedic surgeon. To aid in the accuracy of this process, several types of Computer-Aided Orthopedic Surgery (CAOS) are currently being developed. In general, CAOS involves a three step process: (1) generating a three-dimensional (3D) computerized model of the patient""s bone; (2) performing a computer-aided pre-surgical analysis to generate a surgical plan that instructs a surgeon how to cut, fill, and/or reposition the bone as well as how to manipulate a robot during surgery; and (3) performing computer-aided surgery based on the pre-surgical plan.
The current methods of modeling an incorrectly aligned bone often include the use of Magnetic Resonance Imaging (MRI) or Computerized Axial Tomography (CAT) data. These imaging technologies are very expensive and may take an extensive amount of time for which to model a bone. Conventional CAOS methods often include robot-guided surgery or real-time tracking systems using highly technical equipment reserved for a few select surgeons in a very few locations. Therefore, a need has been recognized to provide the accuracy benefits of CAOS in a more cost effective, easy to use, and more widely available process than a conventional CAOS procedure. This improved CAOS process if preferably available to a wider body of patients and surgeons spread across a greater geographic and economic spectrum than current methods.
The present invention contemplates, in at least one preferred embodiment, devices and methods for computer-aided orthopedic surgery. More specifically, the present invention contemplates devices and methods for performing computer-aided surgical procedures, such as an open wedge osteotomy, using intra-operative feedback to improve the surgical outcome for the patient.
In at least one preferred embodiment of the present invention, a computer database includes one or more template bone models. Multiple X-rays of an incorrectly aligned bone are preferably taken and used to xe2x80x9cmorphxe2x80x9d or modify a stored template bone model to create a 3D model of the misaligned bone. A computer program, running on a planning computer, may be used to aid in the generation of a pre-surgical plan for performing an osteotomy or other orthopedic surgery to correct bone alignment. The pre-surgical plan calculations may include: the positioning of multifunctional markers on the patient""s bone and the parameters for manipulating one or more surgical tools such as an adjustable cutting guide, an adjustable fixation guide, or a combined cutting-fixation guide.
During surgery, a surgeon preferably affixes multifunctional markers to the misaligned bone according to the pre-surgical plan. A new set of fluoroscopic or X-ray images may be taken and used by the planning computer to update the pre-surgical plan into a final surgical plan based on the actual marker positions as depicted in the fluoroscopy. In this way, the updated fluoroscopic or X-ray images act as an intra-operative feedback system.
The surgeon preferably follows the updated surgical plan to cut the bone guided by an adjustable cutting guide and reposition the bone using an adjustable fixation guide (or these guides could be combined) Additionally, for example, in an open wedge osteotomy, the gap between cut sections of the bone are filled by bone graft and a fixation plate is attached thereto to hold the bone in its new orientation.
In at least one preferred embodiment, the planning computer exists at or near the same location as the surgical operating room. In other embodiments, the planning computer, template bone model database, operating room, and any other possible computers or devices may be located remotely from each other. These devices are preferably connected electronically, e.g., by way of the Internet. Such a distributed network allows access to the computer-aided osteotomy resources by an increased number of patients and surgeons than conventional methods. For example, this distributed system may be used to remotely access other experts, such as experienced orthopedic surgeons, during the planning or surgical stages.
These and other details, objects, and advantages of the present invention will be more readily apparent from the following description of the presently preferred embodiments.